Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The size, shape, and weight of rotor blades are factors that contribute to energy efficiencies of wind turbines. An increase in rotor blade size increases the energy production of a wind turbine, while a decrease in weight also furthers the efficiency of a wind turbine. Furthermore, as rotor blade sizes grow, extra attention needs to be given to the structural integrity of the rotor blades. Presently, large commercial wind turbines in existence and in development are capable of generating from about 1.5 to about 12.5 megawatts of power. These larger wind turbines may have rotor blade assemblies larger than 90 meters in diameter. Additionally, advances in rotor blade shape encourage the manufacture of a forward swept-shaped rotor blade having a general arcuate contour from the root to the tip of the blade, providing improved aerodynamics. Accordingly, efforts to increase rotor blade size, decrease rotor blade weight, and increase rotor blade strength, while also improving rotor blade aerodynamics, aid in the continuing growth of wind turbine technology and the adoption of wind energy as an alternative energy source.
One known strategy for reducing the costs of pre-forming, transporting, and erecting wind turbines having rotor blades of increasing sizes is to manufacture the rotor blades in blade segments. The blade segments may be assembled to form the rotor blade after, for example, the individual blade segments are transported to an erection location. Further, in many cases where increased rotor blade sizes are desired, it may be desirable to increase the lengths of existing rotor blades. For example, an existing rotor blade may be divided into segments, and an insert may be provided between neighboring segments to increase the length of the segments.
However, there are concerns associated with such strategies for increasing the size of rotor blades. Particularly when increasing the lengths of existing rotor blades, the structural integrity of such rotor blades is of concern. For example, the existing rotor blade structure may not be sufficient to support the increase in weight due to the addition of an insert to increase the rotor blade size. Additionally, stress concentrations may exist between various segments of a rotor blade that is formed from multiple components.
Various strategies are known for reinforcing rotor blades to ensure the structural integrity thereof. For example, the thickness of the aerodynamic design forming the rotor blade has been increased. However, such increase involves various system performance changes, can substantially increase the weight of the rotor blade, and cannot be utilized when increasing the length of existing rotor blades. Another strategy involves applying glass plies to existing rotor blade shells. However, such strategy has been found to significantly increase the weight of the rotor blade and require an inefficient manufacturing process.
Accordingly, improved wind turbine rotor blades are desired in the art. In particular, rotor blades with improved reinforcement capabilities would be advantageous. Specifically, rotor blades formed from multiple components which include improved reinforcement capabilities are desired in the art.